1. Field of the Invention
The present invention relates to a dielectric resonator for use in, for example, a microwave filter, and more particularly to the improvement of a dielectric block contained in the dielectric resonator.
2. Description of Related Art
Conventionally, in the dielectric resonator of this kind, an arrangement has already been known, for example, as shown in FIG. 14 which is a longitudinal sectional view of a known dielectric resonator to be used in TE.sub.01.delta. mode, the dielectric resonator comprising a metal-made case 2 which accommodates a cylindrical dielectric body 6 having a through hole in the center thereof and a supporting base 4 made of an insulating material which supports the dielectric body 6.
The case 2 is provided with input/output connectors 8 and loop conductors 10 projecting from the case 2 toward the inside thereof. Thus, the loop conductors 10 and the dielectric body 6 are magnetically connected to each other.
In the dielectric body 6, however, an electromagnetic field is generated in, for example, TM mode in some extent other than an electromagnetic field generated in the dominant resonance mode TE.sub.01.delta., namely, an electric field distribution perpendicular to the axis 6z of the dielectric block and a magnetic field distribution in the direction of the axis 6z, thereby to cause a spurious response. In addition, since the dielectric resonator shown in FIG. 14 is comparatively small in its surface area, the heat discharge performance thereof is not favorable. That is, during use, the temperature of the dielectric body 6 rises, with the result that the resonance frequency thereof changes with the change of the dielectric constant thereof or the electrical performance thereof is deteriorated when the dielectric body 6 is used as a filter.